1. Field of the invention
The present invention relates to a polymer linear actuator for a micro electro mechanical system (hereinafter referred to as “MEMS”) and a micro manipulator for a measurement device of a cranial nerve signal using the same, and more particularly to an actuator linearly moving using the thermal expansion of polymer and a micro manipulator for a measurement device of a cranial nerve signal using the same.
2. Description of the Prior Art
As a conventional MEMS type actuator, an actuator using an electrostatic force has been generally used. The MEMS type actuator using an electrostatic force has an advantage in the formation of micro size of such as a micro pattern and the reproducibility thereof through in general using a semiconductor manufacturing process. Such electrostatic actuator has a high response speed and is suitable for the application where to require rapid driving.
The MEMS type linear actuator using an electrostatic force is classified into a type using just an operation manner of a macro scale linear actuator, a type using a inchworm's motion, and a type to improve a displacement through the movement of unrestricted shuttle to overcome a small displacement that is one of the problems of the MEMS type actuator.
However, the conventional electrostatic MEMS type linear actuator has problems of very high operation voltage and a relatively small driving force, in comparison to other type actuator.
Meanwhile, an MEMS type actuator using polymer has also been developed. Such MEMS type polymer rotation actuator has been shown in FIG. 1.
Referring to FIG. 1, the conventional MEMS type polymer rotation actuator 1 includes a base 3, a silicon plate 5 installed on the base 3, and a moving part 7. The moving part 7 is made of silicon like the plate 5 and the two parts are divided by a polymer layer 9. The polymer layer 9 defines the boundary of the moving part 7 and the polymer multi-layers may be installed according to a rotation angle of the moving part 7. The moving part 7 rotates in an arrow direction with the thermal expansion or contraction through the heating or cooling of the polymer layer 9. The rotation movement of the moving part 7 is shown in detail in FIG. 2.
FIG. 2 is an enlarged view of a section A of FIG. 1. In FIG. 2, the polymer layers 9 are installed on the moving part 7 wherein an uncured condition of the polymer layers is indicated in an imaginary line. At this time, when the polymer layers 9 are cured, the moving part 7 is curved and rotated by the contraction thereof as indicated in a solid line. In particular, the lengths a′ and b′ of the upper and lower sides, respectively, of the inverse trapezoid of the polymer layer 9 are reduced to the lengths a and b, respectively, due to its cure. At this time, since the contraction of the upper side of the polymer layer in inverse trapezoidal shape is larger than that of the lower side thereof, the moving part 7 rotates upward by the contraction difference therebetween. The amount of rotation can be regulated with the variation of the number of the polymer layers 9 installed. Accordingly, upon application of heat to the polymer layer 9 cured as shown in solid line, on the contrary, the polymer layer 9 expands so that the moving part 7 rotates in the left side along an arrow direction due to the contraction difference between the upper and lower sides. However, the conventional actuator using the polymer layer can only rotate, but cannot move linearly.